1. Technical Field
The present invention relates generally to power distribution management in electronic systems, and in particular, to a method and system for distributing heat sources among electronic devices having on-board signal terminations. More particularly, the present invention relates to a method and system for strategically enabling and disabling on-die terminations in accordance with power distribution and thermal related factors.
2. Description of the Related Art
Electronic systems using shared bus architectures such as synchronous dynamic random access memory (SDRAM) systems are being fabricated onto increasingly dense circuit structures and are operating at higher speeds, resulting in thermal generation/dissipation problems. An example is double data rate (DDR) SDRAM, which is utilized in high-performance main memory. One solution to the increased localized heat generation is to throttle device/bus operating speeds to a maximum number of cycles over a specified period. By reducing overall power consumption, this approach is effective in reducing heat generation. However, since operating speed is directly or indirectly a system or sub-system parameter, system performance may be unduly compromised and individualized component attention or protection impracticable.
Signal termination is another significant heat contributor in many shared bus systems. Generally, signal termination is utilized to eliminate noise caused by signal reflections on shared transmission paths. Motherboard termination is a termination method that reduces signal reflection by attaching a resistor (termination resistance) having a suitable resistance value to the end of each transmission path. However, this method does not reduce signal reflection sufficiently in the operating frequency range used by DDR2-SDRAM or other very high speed applications. In addition, adding termination resistors to the motherboard increases the component count and raises manufacturing and design costs.
On-die termination (ODT) is an alternate signal termination method that is more effective than motherboard termination in removing signal reflection noise in a shared bus environment having multiple active mode DRAMs that may be affected by reflected signals from DRAMs in a standby mode. For example, DDR2-SDRAM using ODT signal termination contains termination resistors that would otherwise be mounted onto the motherboard, thereby reducing the number of components on the motherboard and simplifying system design.
Both motherboard and ODT types of signal termination release heat as a byproduct of the signal “absorption” process, and therefore may exacerbate heat generation problems in shared bus systems. Accordingly, there is a need for an improved system and method that more effectively manage power distribution in systems using signal terminations. The present invention addresses this need and other needs unaddressed by the prior art.